1. Field of the Invention
The present invention relates to a vibration attenuator for attenuating the vibration caused during machining or resurfacing of a disc brake rotor by a pair of cutter bits.
2. Description of the Prior Art
After a period of use the faces of disc brake rotors of automobiles, trucks and the like become worn unevenly. A characteristic pattern of circumferentially arranged ridges and valleys develops which interferes with optimum braking action. These must be removed by resurfacing or machining. Typically this is done by mounting the rotor on an arbor assembly for rotation by a brake rotor lathe. A pair of cutter bits are moved by the lathe carriage across the faces of the rotating rotor to cut enough of the material away to render the faces flat or planar. During this operation the cutter bits and rotor typically produce loud, screeching noises which are not only unpleasant for the lathe operator and others in the vicinity, but there are accompanying vibrations of the rotor and bits which adversely affect the accuracy of the machining.
Various means have been advanced to attenuate or eliminate such vibrations. One system employs damping pads designed to bear against the opposite faces of the rotor in a position out of the way of the cutter bits. The pads are carried by a relatively complex mounting structure which is secured to the brake lathe. Precise adjustment of the position of the pads is required, and an elaborate linkage arrangement is provided to accomplish this. The arrangement is relatively complex and costly, requires subtle adjustments, and is only partially affective in damping the machining noises.
Another system of the prior art utilizes a resilient band adapted to be stretched and placed upon the circumference of the rotor. One must purchase a set of such bands to accommodate the various sizes of rotor to be machined. The system is unsatisfactory for that reason, and also because the vibration attenuation is not always adequate.
Yet another arrangement of the prior art employs a U-shape rod or handle which mounts a pair of friction resistant pads at its extremities. The pads are placed in position to bear against the opposite faces of the rotor thereby to damp rotor vibrations. However, the pads are not effective to attenuate cutter bit vibrations.